Can the EC elect new EC members?

Dear FlatChat,

The practice at our AGM is to accept and receive the number of nominations
for the EC as being e.g. 7 lot owners putting their hand up plus “1 vacancy” equals 8. It is then resolved to set the number of EC members as eight. Then the seven are elected as members of the new EC, with one vacancy. I am told this is to help with quorum numbers and to give flexibility to the EC if anyone wants to join the EC between AGMs.

1. Is this practice legal?
2. Can the Executive Committee then elect new members to fill a vacancy at an EC meeting or does election have to occur at a general meeting?

Thanks

Jeremy